As a disclaimer, I am (ostensibly enough) not a nail blogger, though my interest in manicures has grown apace. As with all Beauty Primers, the idea is to share what I would have wished to know as a beginner, not necessarily a compendium of all knowledge, so no doubt the information will become outdated in time. For product recommendations, please read the updated Desert Island.

SHAPING
Along with neat cuticles, the shape of the nail determines how the final manicure will look. The eye sees the shape of the polish, first, before it sees the polish. The most flattering shape depends on the size and curve of your nail bed, how much free edge you can access, and personal preference, of course. For most people, something in between a square and an oval (squoval) is most flattering—the pointier it gets, the weaker the nail becomes. File with the old manicure still on. You'll find it easier to gauge the final shape, especially since each nail grows in slightly differently.

The five basic shapes.

Choose a grit that's appropriate to your nail type: the higher the number, the finer the grit. Coarse files take down length faster, especially if you've got strong nails, but a fine grit leave leave a smoother edge and won't tear at thin nails. Crystal files are rightly popular. They take down length efficiently whilst being very gentle. Avoid clippers, as they can split the nail.

Start by lightly neatening the sidewall. Then, in one direction—or, if you find it easier, in two directions working towards the center—reshape and shorten the nail. Maneuver under the nail, as much as possible, so that you clean up any bits and pieces still stuck onto the nail. Check the length of the free edge by flipping your hand over, to see if they line up with each other. Then, to help prevent chipping, you can seal the nail plate with a buffer. If your nails are ridgey, they might benefit from more generalized buffing, which gives a smooth surface for the polish to settle and removes some staining. Since it weakens the nail, however, it's advisable not to buff too often, unless your nails are very thick and strong.

GROOMING CUTICLES
Before you pick a color, the manicure itself must come first. Not even the most spectacular holo looks good against ragged, messy cuticles and misshapen nails. If you moisturize regularly—a lightweight oil and a waxy, protective cream are good in combination—and push them back while they've softened in the shower, they won't require much effort. A good cuticle remover will take care of any excess. If you've neglected them, and your cuticles are tough and overgrown, soak them in warm water first: you can add a drop of soap, some milk (the lactic acid helps soften calluses on the feet), or a tablet of Alka Seltzer, if they've yellowed. It's best however to be consistent with your maintenance, since the nail plate warps ever so slightly when soaked in water. Whatever route you follow, make sure your nails are completely dry before you begin.

Don't be too aggressive. If you tear the cuticle, it damages the nail itself. The gentlest is probably an orange-stick wrapped in cotton, though if you're extremely fastidious and know what you're cutting, a nipper will give the cleanest look.

APPLICATION
To remove nail polish, soak a tightly woven, absorbent cotton in remover and leave on the nail for one to two minutes. Wrap in foil, if you're dealing with something as tenacious as glitter. Give the remover time to sink through layers of polish. It should then wipe off easily, without further damaging the nail. Pure acetone works best, but you can mix in some glycerin to counteracting the drying. If you're prone to bubbling, wipe the surface white vinegar to neutralize any oils.

No one basecoat fits all; choose yours according to the condition of your nails. Some fill in ridges. Others bond tightly to the nail plate. Those formulated with formaldehyde harden the nail plate, conditioners moisturize, while proteins create a protective seal. For further information about nail strengtheners, loodieloodieloodie has written a comprehensive guide. Whichever basecoat works best for you, it should dry quickly, extend the life of your manicure, and minimize staining. Equally critical is a good topcoat. Unless you opt for a special finish (matte, for example), look for a topcoat with a plush, glass-like shine that brings out hidden shimmers in a complex polish, drying quickly without shrinkage. It should seep all the way down to the nail plate, evening out the layers of polish. For thirsty glitters, something like Gelous might be a good investment, to build a cushiony, gel-like layer to fill out the surface before the final topcoat.

Once you're cleaned, shaped, and primed, you're at last ready to color. It takes some practice, but ideally you want to build the polish in thin, even layers. If the polish has separated, roll (not shake) the bottle in the palms of your hands. Start with the pinky, on the nondominant hand; you lose the most dexterity with wet thumbs. You will have much better control if you measure out the amount of polish on the brush, first, so it's easy to apply in deft, sure strokes instead of flooding the nail plate. Don't apply the polish flush with the cuticle: leave a gap so you can shape the polish exactly so. If necessary, clean up any messy edges with a synthetic brush dipped in acetone. If by chance you nick or smudge your manicure, not too badly, lick it to smooth it out. Perhaps the most practical advice is to go to the bathroom before you start your manicure.

The following finishes have categorized more by application style than aesthetics; I suggest reading Lacquerized's guide for the latter:

creme The standard, no shimmer of any kind. Offers the widest range of colors, easiest to mix and match to a pedicure. Look for shades that glow on the nail, instead of looking dull. Alternate finishes that apply much like cremes are neons and mattes, which dry matte. Take especial care with dark vampy shades. They are more likely to stain and require crisp, neat edges and a well shaped nail.

pastel Essentially a creme with white pigment. Tends to have a very thick, chalky flow that will streak on the first coat, so you may need more polish. Consequently, a pastel takes longer to dry. Most yellows have this issue. N.B. a very low amount of ultrafine shimmer usually alleviates the streakiness of a pastel, if you do not insist on a true creme.

sheer Translucent coverage that allows the natural tone of the nail bed to show through. Prone to streakiness, so position the brush parallel to the surface and swipe with the flat of the brush (as opposed to perpendicular).

jelly Differs from the sheer in its squishy gel texture. Applies easily, dries quickly, just be wary that it will never be true-to-bottle.

frost, pearl, and metallic There are many finer gradations within shimmers, from the complexity of glass-flecked duochromes to a fine, evenly metallic foil. Frosts in particular are prone to brushstrokes. Don't work a shimmer polish too much; when dragged across the surface of the nail, the particles can trap minute air bubbles, and bubble like mad. When mixed into a creme base, shimmers are easier to apply.

holo When the shimmer catches the light, it takes on a rainbow hue. Linear holos apply as smoothly as the best cremes, but seem to chip easily, so pair with a bonding basecoat. Like any shimmer, scattered holos can bubble when overworked.

glitter Glitters vary the most in size and shape, from concentrated glass flecks, which bridge the boundary between shimmer and glitter, to small hearts and stars that must be individually placed. Most glitters are best deployed as topcoats or gradients, so the ideal suspension is a smooth gel, with the glitters sparsely distributed. (Pigmentation is not a boon here.) This prevents too much dragging on your manicure. Always look at what's on the brush first, so you've a good idea of what will end up on the nail.

In general, look for a formula that flows smoothly and evenly, with pigmentation that achieves opacity in two coats; at three or four coats, your manicure will take longer to dry. Keep the thinner on standby, as all formulas inevitably thicken. The brush itself also makes a difference: whether you prefer thin or wide, one that keeps its shape, without splaying, is preferable.

There are a few things you can do to extend the life of your manicure, if longevity is a concern. Switch to a bonding basecoat, such as Orly Bonder or Creative Nail Design Stickey, which is designed to grip to nailpolish. Certain formulas are more prone to chips. The more polish sits on the nail, the more readily it will chip: thin layers of a fluid formula is ideal, not too many coats. Every two or three days, you can seal in your manicure with extra topcoat. But most of all, don't deploy your nails as tools. Your manicure is especially vulnerable when wet, so take especial care while showering, cooking, and cleaning dishes (use gloves).

Since I rarely try anything beyond a plain manicure, I cannot speak on nail art: konad, marbling, painting little pictures with a teeny-tiny brush, the French manicure in all its iterations.